Heterosynaptic plasticity prevents runaway synaptic dynamics. Chen JY, Lonjers P, Lee C, Chistiakova M, Volgushev M, Bazhenov M. J Neurosci. 2013 Oct 2;33(40):15915-29.

Spike timing dependent plasticity (STDP) modifies synaptic strength depending on the relative timing of pre-synaptic input and post-synaptic spikes. The effects of STDP in computational models often lead to physiologically inaccurate or unstable distributions of synaptic strength. Examples of stable but physiologically unrealistic synaptic strength distributions include bimodal distributions and highly skewed distributions. Connection strengths also tend to be excessively unstable for learning. Preventing this “run-away” dynamics using basic STDP mechanisms requires fine tuning of learning rules and ...

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Apis mellifera octopamine receptor 1 (AmOA1) expression in antennal lobe networks of the honey bee (Apis mellifera) and fruit fly (Drosophila melanogaster). Sinakevitch IT, Smith AN, Locatelli F, Huerta R, Bazhenov M, Smith BH. Front Syst Neurosci. 2013 Oct 25;7:70.

Octopamine (OA) underlies reinforcement during appetitive conditioning in the honey bee and fruit fly, acting via different subtypes of receptors. Recently, antibodies raised against a peptide sequence of one honey bee OA receptor, AmOA1, were used to study the distribution of these receptors in the honey bee brain (Sinakevitch et al., 2011). These antibodies also recognize an isoform of the AmOA1 ortholog in the fruit fly (OAMB, mushroom body OA receptor). Here we describe in detail the distribution of AmOA1 ...

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Multipulse phase resetting curves. Krishnan GP1, Bazhenov M, Pikovsky A. Phys Rev E Stat Nonlin Soft Matter Phys. 2013 Oct;88(4):042902

In this paper, we introduce and study systematically, in terms of phase response curves, the effect of dual-pulse excitation on the dynamics of an autonomous oscillator. Specifically, we test the deviations from linear summation of phase advances resulting from two small perturbations. We analytically derive a correction term, which generally appears for oscillators whose intrinsic dimensionality is >1. The nonlinear correction term is found to be proportional to the square of the perturbation. We demonstrate this effect in the Stuart-Landau ...

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Age dependency of trauma-induced neocortical epileptogenesis. Timofeev I1, Sejnowski TJ, Bazhenov M, Chauvette S, Grand LB. Front Cell Neurosci. 2013 Sep 18;7:154.

Trauma and brain infection are the primary sources of acquired epilepsy, which can occur at any age and may account for a high incidence of epilepsy in developing countries. We have explored the hypothesis that penetrating cortical wounds cause deafferentation of the neocortex, which triggers homeostatic plasticity and lead to epileptogenesis (Houweling etal., 2005). In partial deafferentation experiments of adult cats, acute seizures occurred in most preparations and chronic seizures occurred weeks to months after the operation in ...

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Our research on epileptic seizures prediction is awarded by grant from the National Institute of Neurological Disorders and Stroke

Epilepsy comprises a group of disorders of the brain characterized by the periodic and unpredictable occurrence of seizures. Reliable means of detecting changes which occur during the pre-seizure state could serve as a method of seizure prediction, a benchmark in epilepsy research. A fast optical signal that coincides with the actual onset of neural activity has been observed both in vitro and in vivo. Pre-seizure fast optical signal, characterized by a reduction in near-infrared (NIR) optical scattering, occurs seconds to ...

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Apis mellifera octopamine receptor 1 (AmOA1) expression in antennal lobe networks of the honey bee (Apis mellifera) and fruit fly (Drosophila melanogaster). Sinakevitch IT, Smith AN, Locatelli F, Huerta R, Bazhenov M, Smith BH. Front Syst Neurosci. 2013 Oct 25;7:70.

Octopamine (OA) underlies reinforcement during appetitive conditioning in the honey bee and fruit fly, acting via different subtypes of receptors. Recently, antibodies raised against a peptide sequence of one honey bee OA receptor, AmOA1, were used to study the distribution of these receptors in the honey bee brain (Sinakevitch et al., 2011). These antibodies also recognize an isoform of the AmOA1 ortholog in the fruit fly ...

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Our research on sleep and memory consolidation is awarded by grant from the Office of Naval Research.

During slow-wave sleep, the cortex is decoupled from external inputs, and can be devoted to consolidating previously acquired labile memories into stable memories. Recently, memory replay has been demonstrated during sleep, and associated with characteristic oscillations, giving rise to the hypothesis that these may form the critical neural substrate of memory consolidation. However, these studies have mainly focused on the rat hippocampus; while replay has also been demonstrated in other structures and species, evidence remains sparse, especially concerning the specific ...

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Dynamics of high-frequency synchronization during seizures. Krishnan GP, Filatov G, Bazhenov M. J Neurophysiol. 2013 May;109(10):2423-37.

The role of changes in ion concentrations in epilepsy remains unclear. It had been long known that increase of [K+]o (Hodgkin and Horovicz, 1959) and/or decrease of [Ca2+]o (Frankenhauser and Hodgkin, 1957) lead to neuronal hyperexcitability and possible epilepsy. But, in epilepsy, the exact mechanisms of the ionic changes, and the contributions of network dynamics remain to be clarified. Here we used multi electrode array (MEA) recordings combined with K-selective electrode and optical measurements from in vitro hippocampal ...

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